Wheel dressing is an integral part of the grinding operation in a computer numerically controlled machine. During a grinding operation, the surface of the wheel may become distorted or clogged. In a dressing operation, the grinding wheel is dressed to expose a new grinding surface. Dressing is accomplished by engaging the grinding wheel with a wheel dresser.
Grinding wheels may be employed in conventional grinding operations or in so-called “viper” grinding. In viper grinding, a grinding wheel is applied at high speeds to a workpiece to cause a relatively high rate of material removal from the workpiece relative to the material removal rate of conventional grinding operations. Viper grinding is characterized most typically by employing a porous grinding wheel and a coolant nozzle that sprays coolant onto the grinding wheel at higher-than-typical coolant pressures. Conventional coolant pressures in a CNC machine are about 100 psi; in viper grinding, the pressure can be approximately 1000 psi. Viper grinding is discussed in more detail in U.S. Pat. No. 6,123,606, hereby incorporated by reference in its entirety for its disclosure of a grinding process.
In viper grinding operations, the grinding wheel is rapidly depleted. The volume of material removed from a workpiece may be compared to the volume of material removed from a grinding wheel in a measurement know as the G-ratio. Whereas, in conventional grinding operations, a G-ratio of approximately 100:1 is typical, viper grinding operations often run at a G-ratio of around 4:1. Accordingly, dressing typically is required at more frequent intervals than in conventional grinding operations.
Conventional CNC machines employ a stationary wheel dresser. The conventional arrangement is effective for dressing the grinding wheel, but can make for a time-consuming dressing operation. This is particularly the case in connection with viper grinding operations, where dressing is required frequently. Efforts have heretofore been made to address the foregoing shortcoming. U.S. Pat. No. 6,666,748, assigned to Makino Milling Machines Company, Ltd., purports to disclose a machining center that includes a specially designed dressing tool disposed over the spindle head of the machining center. This dressing tool is said to assist in automating a dressing process.
The present invention seeks, in some embodiments, to provide a machine, and in other embodiments, a method, that differs from the heretofore described conventional arrangement and from the apparatus and method described in U.S. Pat. No. 6,666,748.